1. Field of the Invention
The present invention relates to a packaging method for an electronic element, and more particularly to a packaging method for an IC or an LED and that lowers the cost of the IC or LED package.
2. Description of Related Art
Semiconductors are used with virtually all electronic equipment including personal computers, cell phones and automated teller machines (ATM). These pieces of equipment all have printed circuit boards (PCB) with IC chips and other electronic elements derived from semiconductor technologies. One of the semiconductor technologies is a packaging technology.
With reference to FIGS. 9 and 10, a conventional packaging method for an integrated circuit (IC) or a light emitting diode (LED) in accordance with the prior art comprises:
bonding an IC die (70) or an LED die (70a) respectively to a lead frame (60) or a copper clad laminate (60a);
bonding multiple wires (71, 71a) respectively from multiple solder points on the IC die (70) and LED die (70a) respectively to multiple pins (61, 61a); and
encapsulating the IC die (70) and LED die (70a) with an encapsulant (72, 72a) respectively to form an IC or LED device.
However, bonding wires (71, 71a) from the IC die (70) and the LED die (70a) respectively to the pins (61, 61a) have unpredictable affects on the physical characteristics of the IC and LED devices such as heat conduction, inductance and impedance. Furthermore, positioning and attaching the wires (71, 71a) significantly reduces the production rate of the IC or LED devices.
With reference to FIGS. 11, 12 and 13, another conventional packaging method in accordance with the prior art for an IC device is a flip-chip packaging method comprising:
attaching multiple solder balls (81) onto a top surface of a die (80);
flipping the die (80) to position the solder balls (81) at desired locations on a lead frame (91) or printed circuit board (90a);
melting and solidifying the solder balls (81) to securely bond the flipped die (80) to the lead frame (91) or printed circuit board (90a); and
encapsulating the die (80) with an encapsulant (95, 95a).
The flip-chip packaging method prevents irregularities in the physical characteristics of the die caused by the bonding wires.
However, the flip-chip packaging method has the following disadvantages:
1. The solder balls (80) are made of tin (Sn) or an alloy of tin and lead (Pb). The process of attaching the solder balls (80) to the die (80) is complicated and tedious and takes time. To attach the solder balls (80), manufacturers must invest a lot of money to open an additionally production line with additional expensive processing equipment.
2. The die is made of a segment of a silicon wafer, GaAs or Sapphire that is fragile and the metal bonding pad is very poor on adhesion. Attaching solder balls (80) directly to the die (80) with a poor adhesion bonding pads has a high probability of damaging or destroying the die (80) during the packaging process. Some types of dies (80) are too thin or small to attach solder balls (80). The flip-chip packaging method can be used only in a small set of circumstances.
To overcome the shortcomings, the present invention provides a packaging method for an IC and LED to mitigate or obviate the aforementioned problems.